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J-14
3 Wiring
3.4 Selection of the Platinum Resistance Thermometer Sensor
FX
3G
/FX
3U
/FX
3UC
PLC User's Manual - Analog Control Edition
FX
3U
-4AD-PTW-ADP (4-channel Platinum Resistance Thermometer Data Input)
3.4 Selection of the Platinum Resistance Thermometer Sensor
Select the Pt100 3-wire platinum resistance thermometer sensor.
This thermometer will not be affected by voltage drop in the wiring area, and will ensure accurate
measurement.
3.5 Wiring of the Platinum Resistance Thermometer Sensor
*1. Separate the cable of the platinum resistance thermometer sensor from the other power cables or
areas easily affected by inductive noise (of the commercial power, etc.).
3.6 Grounding
Grounding should be performed as stated below.
• The grounding resistance should be 100Ω or less.
• Independent grounding should be performed for best results.
When independent grounding is not performed, perform "shared grounding" as shown in the following
figure.
→ For details, refer to the User’s Manual - Hardware Edition of the PLC Series.
• The grounding wire size should be AWG22 to 20 (0.3 to 0.5 mm
2
).
• The grounding point should be close to the PLC, and all grounding wires should be as short as possible.
100k
Ω
ch
PTW-ADP
Class-D grounding
+5V
24+
24-
Twisted shielded
cable
*1
Terminal
block
24V DC
L
+, L
-, I
-, ch
:
represents the channel number.
Pt100
100k
Ω
4.7k
Ω
4.7k
Ω
+5V
100k
Ω
ch
+5V
100k
Ω
4.7k
Ω
4.7k
Ω
Pt100
L
-
I
-
L
+
L
-
I
-
L
+
Shield
Twisted shielded
cable
*1
PLC
Other
equipment
PLC
Other
equipment
PLC
Other
equipment
Shared grounding
Good condition
Common grounding
Not allowed
Independent grounding
Best condition